How much salt is enough? Researchers say we need to think again!
We are all familiar with the health warnings that tell us to reduce our salt intake if we want a happy heart. But now, new findings from an international team of researchers suggest that having either excessively high or low levels of salt can put people who suffer from conditions such as heart disease or diabetes more at risk of cardiovascular problems. Researchers from Canada, Germany, Ireland, the Philippines and the United Kingdom contributed to the study, published in the Journal of the American Medical Association. The findings could call into question how we view the relationship between salt and heart problems. Their findings confirm, as expected, that moderate salt intake is associated with the lowest risk of cardiovascular problems. Yet they also show that while a higher intake of salt was associated with an increased risk of a stroke, a heart attack or other cardiovascular condition, low intake was associated with an increased risk of cardiovascular death and hospitalisation for congestive heart failure. The team obtained the results for this study by examining 28 880 people who were at risk of heart disease, and looked at the relationship between cardiovascular activity and sodium excretion, as a way of measuring sodium consumption. Sodium is the main component of salt. One of the study authors, Professor Martin O'Donnell from the National University of Ireland (NUI) Galway, explains how these new findings fit into the existing body of research on this topic: 'This research addresses an important population health issue - the association between sodium (salt) intake and cardiovascular disease. This area has become topical again, with the recent publication of another paper in the Journal of the American Medical Association reporting an association between low sodium intake and cardiac death. In general, previous observational studies have either reported a positive association, no association or an inverse association between sodium intake and heart disease and stroke. This has resulted in a lot of controversy.' Concerning this latest research, he notes: 'Our study is the first to report a J-shaped association between sodium intake and cardiovascular disease, which may explain why previous studies have found different results.' So how can we win? Is it a case of damned if we do and damned if we don't? The findings certainly call into question current World Health Organization (WHO) guidelines for salt intake that advise consuming less that 2.3 grams per day. These guidelines are mostly based on previous clinical trials that found blood pressure is lowered modestly when sodium intake is reduced to these levels, as was also confirmed in this new study. But the research gap identified by the team refers to a failure to explore this result further and to ascertain whether such low levels of sodium intake reduce the incidence of heart attacks and stroke. For patients who already suffer from heart disease, it is vital that the optimal daily intake of sodium is clarified: they could be both vulnerable to the effects of both very high and very low salt intakes. Yet under current thinking in the medical world, they are most likely to be advised to reduce salt intake. 'Our research confirms the association between high sodium intake and increased risk of cardiovascular disease, which emphasises the importance of salt reduction in those consuming high-sodium diets (over 6 g to 7 g per day) and the importance of efforts to reduce sodium content of many high-salt manufactured foods,' said Professor O'Donnell. However, he voiced concerns for the 'uncertainty about whether those with moderate/average sodium intake should reduce their intake further'. 'The only way to resolve this uncertainty is with a large randomised controlled trial that determines whether reducing moderate sodium intake to lower levels results in lower rates of heart disease and stroke. While we accept there are challenges to conducting such trials, they are required urgently given their public health implications,' emphasised Professor O'Donnell.For more information, please visit:NUI Galway:http://www.nuigalway.ie/
Countries
Canada, Germany, Ireland, Philippines, United Kingdom